IMSA’s 1992 fuel regulations stated simply that “Class-A” gasoline that met the American Society of Testing and Materials (ASTM) D-439 standards was eligible for competition in the IMSA GTP series as long as it didn’t exceed a specific gravity of .750.  At their discretion, IMSA reserved the right to sample and verify that the fuel was conforming to the ASTM specification; this comes straight from the IMSA code, Article 11.3.  But by mid-season it became evident that the fuel regulations were being pressed rather hard.  According to TWR Jaguar Manager Tony Dowe, “I certainly was not backward in pushing the view that Toyota was running illegal fuel. It was very obvious that the boost levels that were being used were not sustainable using legal fuel.”  In the mean time TWR itself was using a special brew concocted for the Benetton Formula 1 team for use in the Ford HB 3.5 liter V8.  “It was within the rules as far as the rules went.  However, it was quite toxic until it was burnt, hence why our guys used breathing gear when handling it.”  With all the appearance of improprieties going on, IMSA decided to investigate the situation.   

At the Watkins Glen round IMSA took fuel samples from three competitors; the #83 Nissan, #99 Toyota, and the #2 Jaguar, and had them tested by Exxon off the record.  “Exxon did not want to be involved with any litigation, they did not want to be involved with any repercussions or fallout,” says Jim Woodward, IMSA Technical Director.  In the end Exxon was simply used to determine if the issue had any teeth and was worth pursuing or not. 

When the Toyota sample showed to be “way out” of specification, AAR was presented with the results and was subsequently deferred to Drino Miller and TRD, says Woodward, “Gurney had no idea what it (the fuel) was and said I’d have to talk to Drino.”  Woodward immediately attempted to reach Drino but he had already left the office for the Road America round, “We were prepared to take samples but hadn’t made the decision, we were still trying to work it out.”  Woodward spoke with Miller first thing at Road America and Drino, “Presented no chance of compromise.  He told us that we needed to do what we had to do.” 

During the race IMSA sent five groups of scrutineers to take fuel samples from the top five competitor’s refueling rigs.  The samples were all taken simultaneously and were drawn from Nissan (#83), the Joest Porsche 962C (#30), Mazda (#77), and the two Toyotas (#98 & 99), and sent blind (samples A, B, C, D, and E) to Core Laboratories in Houston Texas, an American Society for Testing and Materials (ASTM) certified laboratory.  They were then tested against the ASTM 439-89 specification for automobile gasoline. 

The primary test consisted of boiling the fuel samples and noting the temperatures at which 5%, 10%, 20%, 30%, etc., 95% evaporated off.  This distillation finger print would then give an indication of the nature of the fuel make up, heavier vs. lighter elements, with the heavier elements being conducive to power generation.   The more temperature it took to burn off a percentage of the weight indicated heavier chemical components.

While the test results were pending the Road America race results were listed as provisional.

IMSA received the test results from Core Labs by late August, though they had been in constant phone contact and had a heads up as to what to expect and had subsequently been planning how to react.  Despite the outward appearance of a witch hunt, there was much hand wringing within IMSA.  IMSA didn’t like the prospects of what the test results told any more than anyone else; 4 out of the 5 fuel samples did not meet the ASTM standard and were therefore illegal.  The #77 Mazda RX-792P was the only car that was deemed to be within the regulation.

IMSA was conscious of the potential fire storm and didn’t come to any conclusions easily.

IMSA responded by initially stating that the accused teams would loose their points from Road America.  That was met with resounding indignation and reaction from the accused was swift. 

TRD and Drino Miller, as laid out in On Track magazine, began to publicly formulate a potential legal stance in order to challenge, and have thrown out, the fuel test results.  The argument was that ASTM guidelines specifically stated the temperature, between 32 and 40 degrees Fahrenheit, at which the fuel samples should be drawn and subsequently stored and shipped. 

TRD wasn’t alone, “I wrote a long rebuttal to IMSA refuting the results based on the fact that the fuel sample collection, handling and storage procedures did not conform to the ASTM specification governing the sample collection process, which could in turn lead to erroneous test results,” says Nissan’s Wes Moss.  The concerns were that with the high ambient temperatures at which the fuel was drawn and shipped, lighter elements in the fuel could have been allowed to evaporate off leaving a less representative sample from which the distillation fingerprint was taken, thus making what was potentially legal, illegal against the ASTM specification.

But there were also rumors of a lawsuit being filed behind the scenes, to the tune of $6,000,000.

Ultimately IMSA was in weak legal standing by not following the ASTM guidelines to the letter.  In the end it didn’t really matter that the test samples taken at Watkins Glen and Road America (and tested by different labs) showed effectively identical distillation fingerprints, putting into question the actual affect the sampling temperature had on the results.  Additionally the extraordinary high level of toluene in the Toyota samples (81.96%) was noteworthy and wouldn’t have been affected by temperature issues.  Toluene is typically used to increase a fuel’s knock (pre-detonation) resistance, a necessity when increasing turbo boost levels.  But since IMSA’s fuel regulations didn’t actually state what could or couldn’t be in the fuel other than it had to pass the ASTM D439-89, this was immaterial.  Ultimately the lesson was that it was clear some of the competitors were perhaps within the letter of fuel regulation law if not the spirit.

The result was that IMSA backed down rather than go head-to-head with a protracted legal fight.  All of the competitors were cleared on appeal.  The provisional results from Road America were certified and the fines rescinded.